The present invention relates to a copier, facsimile apparatus, printer or similar image forming apparatus having a function of erasing an image recorded on a sheet by a recording agent which is implemented by a decolorizable coloring agent.
Papers wasted in offices are one of various wastes taking growing interest from the standpoint of, among others, the protection of natural resources. To reduce waste papers, recycling documents used in offices, i.e., so-called OA (Office Automation) sheets is desperately needed today. At the present stage of development, rerecycling OA documents requires collection of OA sheets used by, e.g., a copier or a printer while classifying them, melt them, remove ink, and then make sheets. Sheets regenerated by such a procedure are reused. However, it has been reported that only 5 percent of as great as 250,000 tons of OA sheets consumed in offices is collected now as matters stand.
On the other hand, there has been proposed another type of OA sheet recycling system wherein images are printed on OA sheets by using a toner, ink or similar recording agent implemented by a decolorizable coloring agent. In this type of scheme, when the OA sheets with images become needless, the toner or ink is removed from the sheets to allow other images to be newly printed on sheets, i.e., to implement OA recycling within the office. Consisting of a cyanin-based coloring matter and ammonium salt, the decolorizable coloring agent loses color when irradiated by light having a wavelength range of 820 nm or so. For example, in an ordinary electrophotographic image forming apparatus, when this kind of coloring agent is substituted for carbon black which is the coloring agent of the apparatus, images printed on sheets appear blue under usual illumination and are as legible as ordinary recordings. By forming images on OA sheets using such a unique coloring agent, it is possible to regenerate used sheets relatively easily. This is extremely useful to save natural resources, to preserve the environment, and to reduce wastes.
A device for erasing images formed on sheets by the decolorizable coloring agent has been proposed in some forms in the past. However, all of them are constructed as a unit and used independently of an image forming apparatus. Therefore, to reuse sheets, it is necessary to decolorize the images of the sheets by the erasing device, and then load the decolorized sheets on the image forming apparatus, slowing down the image forming operation.